Tuesday, May 31, 2011

புதன் என்னும் மாயகிரகம் ! ''பொன் கிடைக்தாலும் புதன் கிடைக்காது'..புதன் கிடைத்துவிட்டது, பொன்தான் கிடைக்காது போல இருக்கின்றது.

புதன் என்னும் மாயகிரகம் !

புகழ்பெற்ற வானியல் விஞ்ஞானி கோப்பர்னிக்கஸ் மரணப்படுக்கையில் கிடக்கும் போது கடைசிவரை என்னால் புதன் கிரகத்தைப் பார்க்க முடியாமல் போய்விட்டதே என்று வருத்ததுடன் கூறினாராம். அவரால் பார்க்க முடியாமல் போனாலும் தற்போதைய தலைமுறைக்கு புதன் கிரகத்தின் படங்களையும், அதைபற்றிய தகவல்களையும் தெரிந்து கொள்ளும் வாய்ப்பை மெசஞ்சர் விண்கலம் ஏற்படுத்தியிருக்கிறது.

சூரியகுடும்பத்தின் முதல்கிரகம் புதன். பூமியை போல புதன் தன்னை தனே சுற்றிக்கொள்வதில்லை. சூரியனை சுற்ற அது எடுத்துக்கொள்ளும் காலம் 88 நாட்கள். சூரியனிலிருந்து 6 கோடி கிலோமீட்டர் தொலைவில் உள்ளது.அதன் பகல் பொழுது வெப்பம் 400 டிகிரி செல்சியஸ், இரவு பகுதி வெப்பம் - 260 டிகிரி செல்சியஸ். ஒரு செகண்டிற்கு 29.4 கிலோமீட்டர் வேகத்தில் சுற்றுகிறது. பூமியில் 18 புதன் கிரகங்களை போட்டு நிரப்பிவிடலாம், அந்த அளவுக்கு சிறியது. இது போன்ற தகவல்களை தொலைநோக்கிகள், கணக்கீடுகள் மூலம் விஞ்ஞானிகள் கண்டுபிடித்தார்கள்.

1973ம் ஆண்டு அமெரிக்காவால் அனுப்பட்ட மாரினார் 10 விண்கலம் ஒரு புதிய தகவலை சொன்னது. புதன் கிரகத்தின் அடர்த்தி அதிகம். வெள்ளி, பூமி, செவ்வாய் கிரகங்களில் பாறை பகுதி 70 சதமாகவும் 30 சதம் இரும்பு உள்ளடக்கமாகவும் இருக்கிறது.புதனில் 30 சதம் பாறை பகுதியும், 70 சதம் இரும்பு உள்ளடக்கம் கொண்டதாகவும் இருக்கிறது.

1977ம் ஆண்டு அனுப்பட்ட வாயேஜர்- 2 விண்கலம் வியாழன், சனி, யூரேனஸ், நெப்டியூன் கிரகங்களை ஆராய்ந்துவிட்டு சூரியமண்டலத்தின் எல்லையைத் தாண்டி சென்றுவிட்டது. வியாழன் கிரகத்தை கலிலியோ விண்கலம் 1995 முதல் 14 ஆண்டுகள் ஆராய்ந்தது. 2004ம் ஆண்டு முதல் சனிகிரகத்தை காசினி விண்கலம் சுற்றி வருகிறது. வெள்ளி கிரகத்தை மெகல்லன் விண்கலம் போன்ற பல விண்கலங்கள் மூலம் ஆராயப்ட்டுள்ளது. ஆனால் புதன் கிரகத்தின் மீது விஞ்ஞானிகளின் பார்வை திரும்பவேயில்லை.

புதன் கிரகத்திற்கு விண்கலத்தை அனுப்புவதில் பிரச்சனைகள் உண்டு. பூமியானது சூரியனில் இருந்து சுமார்15 கோடி கி.மீ. தொலைவில் உள்ளது. புதன் சூரியனிலிருந்து வெறும் 6 கோடி கி.மீ. தெலைவில் உள்ளது.புதன் கிரகத்திற்கு விண்கலத்தை அனுப்புவது சூரியனை நோக்கி அனுப்புவதற்கு சமம்.இதில் இரண்டு பிரச்சனைகள் உண்டு. வெப்பம் அதிகரிக்கும், மேலும் விண்கலத்தின் வேகம் அதிகரிக்கும்.புதன் கிரகத்தை செல்வதற்கு பதிலாக சூரியனைநோக்கி சென்று சாம்பலாகிவிடும். புதன் கிரகத்தை நெருங்கி புதன் கிரகத்தின் ஈர்ப்பு பிடியில் சிக்குகிற அளவுக்கு விண்கலத்தின் வேகம் குறைந்தால்தான் விண்கலம் புதன் கிரகத்தை சுற்ற ஆரம்பிக்கும். வேகத்தை குறைப்பது தான் பிரச்சனை.

2004 ஆகஸ்டில் அனுப்பபட்ட மெசஞ்சர் வினாடிக்கு 640 கிலேமீட்டர் வேகத்தில் பயணம் செய்தது. இதன் வேகத்தை படிப்படியாக குறைக்க புதிய வழி கையாளப்பட்டது.இதன் படி மெசஞ்சர் விண்கலம் சூரியனை ஒரு சுற்றுசுற்றிவிட்டு மறு ஆண்டு ஆகஸ்டில் பூமியை நெருங்கியது. அப்போது அதன் வேகம் சற்று குறைந்தது.பின்னர் மேலும் சில சுற்றுகள் சுற்றிவிட்டு வெள்ளி கிரகத்தை 2006 - மற்றும் 2007ம் ஆண்டில் கடந்து சென்றது. அதனால் மேலும் வேகம் குறைக்கப்பட்டது. பின்னர் சூரியனை மேலும் சிலமுறை சுற்றிக்கொண்டே புதன் கிரகத்தை நெருங்கியது.இந்த ஆண்டு மார்ச் 18ம் தேதி புதன் பிடியில் சிக்கி சுற்ற ஆரம்பித்தது. அமெரிக்க நாசா விண்வெளி அமைப்பை சேர்ந்த சென்வான்யென் எனபவர்தான் மெசஞ்சர் விண்கலத்தின் பாதையை திட்டமிட்டு கொடுத்தார்.

பூமியிலிருந்து புதன் கிரகம் அதிகபட்சமாக 22 கோடி கிலோமீட்டர் துரத்தில் தான் உள்ளது. 2004 ம் ஆண்டில் செலுத்தபட்ட மெசஞ்சர் ஆறரை ஆண்டுகாலம் விண்ணில் அங்கும் இங்குமாக வட்டமடித்து புதனை நெருங்கிய போது அது பயணம் செய்த தூரம் 790 கோடி கிலோ மீட்டர். சூரியனின் அதிகமான வெப்பத்தை தாங்க காப்பு கேடயம் தாயாரிக்க மட்டும் 7 ஆண்டுகள் பிடித்தன. மேலும் விண்கலத்தை உருவாக்கதிட்டம், அதை செய்துமுடிக்க ஆகும் காலம், பாதை உத்திகளை உருவாக்க என சுமார் 20ஆண்டுகள் பிடித்தன.

மெசஞ்சர் விண்கலம் 363 புகைப்படங்களை எடுத்து அனுப்பியுள்ளது. அதை ஆராய்ந்த விஞ்ஞானிகள் அதன் இருட்டு பகுதியில் ''டெபுசி'' என்று அழைக்கப்படுகிற கதிர்வீச்சு காணப்படுவதாகவும். அதன் பகல் பகுதியும், இருள்பகுதியும் சந்திக்கும் பகுதியில் ஒளிவட்டம் போன்ற வளையம் இருப்பதாகவும் சொல்கிறார்கள். மெசஞ்சர் மேலும் அனுப்புகிற தகவல்களை கொண்டு புதன் என்னும் மாய உலகத்தை பற்றி தெரிந்து கொள்ளலாம்.

புதன் கிரகத்தை பற்றி ''பொன் கிடைக்தாலும் புதன் கிடைக்காது'' என்ற மிக பிரபலமான சொலவடை தமிழகத்தில் உள்ளது. புதனை வெறுங்கண்ணால் பார்க்க இயலும் என்றாலும் எளிதில் தென்படாது. சூரியனுக்குப் பக்கத்தில் இருப்பதால் அதிகாலையில் கிழக்குப்பக்கம் சூரிய உதயதிற்கு முன்னால் சிறிது நேரம் தெரியும், அல்லது மாலை நேரம் சூரிய அஸ்தமனத்திற்கு பிறகு மங்களான சிறிய புள்ளியாகத் தெரியும். மெசஞ்சர் விண்கலம் மூலமாக புதன் கிடைத்து விட்டது. பொன்(தங்கம்) தான் எட்டமுடியாத அளவிற்கு விலை ஏறிக்கொண்டே போகிறது

வாழ்க வள்ளுவம்: வளர்க தமிழ் !!! பொருட்பால்:அமைச்சியல்!!! நாடு:அதிகாரம்74/133

by Keyem Dharmalingam on Tuesday, 31 May 2011 at 07:06

வாழ்க வள்ளுவம்: வளர்க தமிழ் !!!

பொருட்பால்:அமைச்சியல்!!!

நாடு:அதிகாரம் 74/133

731.

தள்ளா விளையுளும் தக்காரும் தாழ்விலாச்

செல்வரும் சேர்வது நாடு.

இணைப்பினை அழுத்தி குறட்பாவினை இனிய இசையில் விளக்கத்துடன் கேட்டு மகிழுங்கள்.

<a onClick='window.open("http://www.raaga.com/player4/?id=177304"

Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

Where spreads fertility unfailing, where resides a band,

Of virtuous men, and those of ample wealth, call that a 'land'

Explanation :

A kingdom is that in which (those who carry on) a complete cultivation, virtuous persons, and merchants with inexhaustible wealth, dwell together.

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732.

பெரும்பொருளால் பெட்டக்க தாகி அருங்கேட்டால்

ஆற்ற விளைவது நாடு.

<a onClick='window.open("http://www.raaga.com/player4/?id=177305"

Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

That is a 'land' which men desire for wealth's abundant share,

Yielding rich increase, where calamities are rare.

Explanation :

A kingdom is that which is desire for its immense wealth, and which grows greatly in prosperity, being free from destructive causes.

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733.

பொறையொருங்கு மேல்வருங்கால் தாங்கி இறைவற்கு

இறையொருங்கு நேர்வது நாடு.

<a onClick='window.open("http://www.raaga.com/player4/?id=177306"

Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

When burthens press, it bears; Yet, With unfailing hand

To king due tribute pays: that is the 'land'

Explanation :

A kingdom is that which can bear any burden that may be pressed on it (from adjoining kingdoms) and (yet) pay the full tribute to its sovereign.

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734.

உறுபசியும் ஓவாப் பிணியும் செறுபகையும்

சேரா தியல்வது நாடு.

<a onClick='window.open("http://www.raaga.com/player4/?id=177307"

Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

That is a 'land' whose peaceful annals know,

Nor famine fierce, nor wasting plague, nor ravage of the foe.

Explanation :

A kingdom is that which continues to be free from excessive starvation, irremediable epidemics, and destructive foes.

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735.

பல்குழுவும் பாழ்செய்யும் உட்பகையும் வேந்தலைக்கும்

கொல்குறும்பும் இல்லத

<a onClick='window.open("http://www.raaga.com/player4/?id=177308"

Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

From factions free, and desolating civil strife, and band

Of lurking murderers that king afflict, that is the 'land'.

Explanation :

A kingdom is that which is without various (irregular) associations, destructive internal enemies, and murderous savages who (sometimes) harass the sovereign.

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736.

கேடறியாக் கெட்ட இடத்தும் வளங்குன்றா

நாடென்ப நாட்டின் தலை.

<a onClick='window.open("http://www.raaga.com/player4/?id=177309"

Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

Chief of all lands is that, where nought disturbs its peace;

Or, if invaders come, still yields its rich increase.

Explanation :

The learned say that the best kingdom is that which knows no evil (from its foes), and, if injured (at all), suffers no diminution in its fruitfulness.

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737.

இருபுனலும் வாய்ந்த மலையும் வருபுனலும்

வல்லரணும் நாட்டிற்கு உறுப்பு.

<a onClick='window.open("http://www.raaga.com/player4/?id=177310"

Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

Waters from rains and springs, a mountain near, and waters thence;

These make a land, with fortress' sure defence.

Explanation :

The constituents of a kingdom are the two waters (from above and below), well situated hills and an undestructible fort.

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738.

பிணியின்மை செல்வம் விளைவின்பம் ஏமம்

அணியென்ப நாட்டிவ் வைந்து.

<a onClick='window.open("http://www.raaga.com/player4/?id=177311"

Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

A country's jewels are these five: unfailing health,

Fertility, and joy, a sure defence, and wealth.

Explanation :

Freedom from epidemics, wealth, produce, happiness and protection (to subjects); these five, the learned, say, are the ornaments of a kingdom.

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739.

நாடென்ப நாடா வளத்தன நாடல்ல

நாட வளந்தரு நாடு.

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Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

That is a land that yields increase unsought,

That is no land whose gifts with toil are bought.

Explanation :

The learned say that those are kingdom whose wealth is not laboured for, and those not, whose wealth is only obtained through labour.

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740.

ஆங்கமை வெய்தியக் கண்ணும் பயமின்றே

வேந்தமை வில்லாத நாடு

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Translation by Rev. Dr. G. U. Pope, Rev W. H. Drew,Rev. John Lazarus and Mr F. W. Ellis

Though blest with all these varied gifts' increase,

A land gains nought that is not with its king at peace.

Explanation :

Although in possession of all the above mentioned excellences, these are indeed of no use to a country, in the absence of harmony between the sovereign and the sujects.

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குறட்பா இணைப்புக்களை சேமித்துக் கொள்ளுங்கள் நண்பரே!!! எப்போது வேண்டுமானாலும் எந்த குறள் வேண்டுமானாலும் உங்கள் குழந்தை களுடனோ, நண்பர்களுடனோ இனிய இசையில், விளக்கத்துடன் தமிழில் கேட்டு மகிழ உதவியாக இருக்கும். ஆங்கிலத்திலும் போப், அவர்களால் மொழி...பெயர்க்கப்பட்டு விளக்கத்துடன் கொடுக்கப் பட்டுள்ளது. மேலும் வேறு மொழிகளில் பதிவுகள் கிடைத்தால் நண்பர்களுடன் பகிர்ந்து கொள்ள விருப்பம் உண்டு. விருப்பம் உள்ள அன்பர்கள் நண்பர்கள் தொடர்பு கொள்ளவும். நன்றி.......அன்புடன் கே எம் தர்மா....

Monday, May 30, 2011

Spitzer Sees Crystal 'Rain' in Outer Clouds of Infant Star

NASA's Spitzer Space Telescope detected tiny green crystals, called olivine, thought to be raining down on a developing star. (Credit: NASA/JPL-Caltech/University of Toledo)

Science Daily — Tiny crystals of a green mineral called olivine are falling down like rain on a burgeoning star, according to observations from NASA's Spitzer Space Telescope.

This is the first time such crystals have been observed in the dusty clouds of gas that collapse around forming stars. Astronomers are still debating how the crystals got there, but the most likely culprits are jets of gas blasting away from the embryonic star.

"You need temperatures as hot as lava to make these crystals," said Tom Megeath of the University of Toledo in Ohio. He is the principal investigator of the research and the second author of a new study appearing in Astrophysical Journal Letters. "We propose that the crystals were cooked up near the surface of the forming star, then carried up into the surrounding cloud where temperatures are much colder, and ultimately fell down again like glitter."

Spitzer's infrared detectors spotted the crystal rain around a distant, sun-like embryonic star, or protostar, referred to as HOPS-68, in the constellation Orion.

The crystals are in the form of forsterite. They belong to the olivine family of silicate minerals and can be found everywhere from a periodot gemstone to the green sand beaches of Hawaii to remote galaxies. NASA's Stardust and Deep Impact missions both detected the crystals in their close-up studies of comets.

"If you could somehow transport yourself inside this protostar's collapsing gas cloud, it would be very dark," said Charles Poteet, lead author of the new study, also from the University of Toledo. "But the tiny crystals might catch whatever light is present, resulting in a green sparkle against a black, dusty backdrop."

Forsterite crystals were spotted before in the swirling, planet-forming disks that surround young stars. The discovery of the crystals in the outer collapsing cloud of a proto-star is surprising because of the cloud's colder temperatures, about minus 280 degrees Fahrenheit (minus 170 degrees Celsius). This led the team of astronomers to speculate the jets may in fact be transporting the cooked-up crystals to the chilly outer cloud.

The findings might also explain why comets, which form in the frigid outskirts of our solar system, contain the same type of crystals. Comets are born in regions where water is frozen, much colder than the searing temperatures needed to form the crystals, approximately 1,300 degrees Fahrenheit (700 degrees Celsius). The leading theory on how comets acquired the crystals is that materials in our young solar system mingled together in a planet-forming disk. In this scenario, materials that formed near the sun, such as the crystals, eventually migrated out to the outer, cooler regions of the solar system.

Poteet and his colleagues say this scenario could still be true but speculate that jets might have lifted crystals into the collapsing cloud of gas surrounding our early sun before raining onto the outer regions of our forming solar system. Eventually, the crystals would have been frozen into comets. The Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, also participated in the study by characterizing the forming star.

"Infrared telescopes such as Spitzer and now Herschel are providing an exciting picture of how all the ingredients of the cosmic stew that makes planetary systems are blended together," said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington.

The Spitzer observations were made before it used up its liquid coolant in May 2009 and began its warm mission.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope mission for the agency's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

For more information about Spitzer, visithttp://www.nasa.gov/spitzer and http://spitzer.caltech.edu/

Chameleon Magnets: Ability to Switch Magnets 'On' or 'Off' Could Revolutionize Computing

Theoretical physicist Igor Zutic has been exploring ways to use magnets to revolutionize computing (Credit: Image courtesy of University at Buffalo)

Science Daily — What causes a magnet to be a magnet, and how can we control a magnet's behavior? These are the questions that University at Buffalo researcher Igor Zutic, a theoretical physicist, has been exploring over many years.

He is one of many scientists who believe that magnets could revolutionize computing, forming the basis of high-capacity and low-energy memory, data storage and data transfer devices.

In a recent commentary in Science, Zutic and fellow UB physicist John Cerne, who studies magnetism experimentally, discuss an exciting advancement: A study by Japanese scientists showing that it is possible to turn a material's magnetism on and off at room temperature.

A material's magnetism is determined by a property all electrons possess: something called "spin." Electrons can have an "up" or "down" spin, and a material is magnetic when most of its electrons possess the same spin. Individual spins are akin to tiny bar magnets, which have north and south poles.

In the Japanese study, which also appears in the current issue of Science, a team led by researchers at Tohoku University added cobalt to titanium dioxide, a nonmagnetic semiconductor, to create a new material that, like a chameleon, can transform from a paramagnet (a nonmagnetic material) to a ferromagnet (a magnetic material) at room temperature.

To achieve change, the researchers applied an electric voltage to the material, exposing the material to extra electrons. As Zutic and Cerne explain in their commentary, these additional electrons -- called "carriers" -- are mobile and convey information between fixed cobalt ions that causes the spins of the cobalt electrons to align in one direction.

In an interview, Zutic calls the ability to switch a magnet "on" or "off" revolutionary. He explains the promise of magnet- or spin-based computing technology -- called "spintronics" -- by contrasting it with conventional electronics.

Modern, electronic gadgets record and read data as a blueprint of ones and zeros that are represented, in circuits, by the presence or absence of electrons. Processing information requires moving electrons, which consumes energy and produces heat.

Spintronic gadgets, in contrast, store and process data by exploiting electrons' "up" and "down" spins, which can stand for the ones and zeros devices read. Future energy-saving improvements in data processing could include devices that process information by "flipping" spin instead of shuttling electrons around.

In their Science commentary, Zutic and Cerne write that chameleon magnets could "help us make more versatile transistors and bring us closer to the seamless integration of memory and logic by providing smart hardware that can be dynamically reprogrammed for optimal performance of a specific task."

"Large applied magnetic fields can enforce the spin alignment in semiconductor transistors," they write. "With chameleon magnets, such alignment would be tunable and would require no magnetic field and could revolutionize the role ferromagnets play in technology."

In an interview, Zutic says that applying an electric voltage to a semiconductor injected with cobalt or other magnetic impurities may be just one way of creating a chameleon magnet.

Applying heat or light to such a material could have a similar effect, freeing electrons that can then convey information about spin alignment between ions, he says.

The so-far elusive heat-based chameleon magnets were first proposed by Zutic in 2002. With his colleagues, Andre Petukhov of the South Dakota School of Mines and Technology, and Steven Erwin of the Naval Research Laboratory, he elucidated the behavior of such magnets in a 2007 paper.

The concept of nonmagnetic materials becoming magnetic as they heat up is counterintuitive, Zutic says. Scientists had long assumed that orderly, magnetic materials would lose their neat, spin alignments when heated -- just as orderly, crystalline ice melts into disorderly water as temperatures rise.

The carrier electrons, however, are the key. Because heating a material introduces additional carriers that can cause nearby electrons to adopt aligned spins, heating chameleon materials -- up to a certain temperature -- should actually cause them to become magnetic, Zutic explains. His research on magnetism is funded by the Department of Energy, Office of Naval Research, Air Force Office of Scientific Research and the National Science Foundation

Significant Role Played by Oceans in Ancient Global Cooling

ScienceDaily — Thirty-eight million years ago, tropical jungles thrived in what are now the cornfields of the American Midwest and furry marsupials wandered temperate forests in what is now the frozen Antarctic. The temperature differences of that era, known as the late Eocene, between the equator and Antarctica, were only half of what they are today. A debate has long been raging in the scientific community on what changes in our global climate system led to such a major shift from the more tropical, greenhouse climate of the Eocene to the modern and much cooler climates of today.

New research published in the journal Science, led by Rensselaer Polytechnic Institute scientist Miriam Katz, is providing some of the strongest evidence to date that the Antarctic Circumpolar Current (ACC) played a key role in the major shift in the global climate that began approximately 38 million years ago. The research provides the first evidence that early ACC formation played a vital role in the formation of the modern ocean structure.

The paper, titled "Impact of Antarctic Circumpolar Current development on late Paleogene ocean structure," is published in the May 27, 2011, issue of Science.

"What we have found is that the evolution of the Antarctic Circumpolar Current influenced global ocean circulation much earlier than previous studies have shown," said Katz, who is assistant professor of earth and environmental science at Rensselaer. "This finding is particularly significant because it places the impact of initial shallow ACC circulation in the same interval when the climate began its long-term shift to cooler temperatures."

There has been a debate over the past 40 years on what role the Antarctic Circumpolar Current had in the underlying cooling trend on Earth. Previous research has placed the development of the deep ACC (greater than 2,000 meters water depth) in the late Oligocene (approximately 23-25 million years ago). This is well after the global cooling pattern had been established. With this research, Katz and her colleagues used information from ocean sediments to place the global impact of the ACC to approximately 30 million years ago, when it was still just a shallow current.

Oceans and global temperatures are closely linked. Warmer ocean waters result in warmer air temperatures and vice versa. In the more tropical environs of the Eocene, ocean circulation was much weaker and currents were more diffuse. As a result, heat was more evenly distributed around the world. This resulted in fairly mild oceans and temperatures worldwide, according to Katz. Today, ocean temperatures vary considerably and redistribute warm and cold water around the globe in significant ways.

"As the global ocean currents were formed and strengthened, the redistribution of heat likely played a significant role in the overall cooling of the Earth," Katz said.

And no current is more significant than the ACC. Often referred to as the "Mixmaster" of the ocean, the ACC thermally isolates Antarctica by preventing warm surface waters from subtropical gyres to pass through its current. The ACC instead redirects some of that warm surface water back up toward the North Atlantic, creating the Antarctic Intermediate Water. This blocking of heat enabled the formation and preservation of the Antarctic ice sheets, according to Katz. And it is this circumpolar circulation that Katz's research concludes was responsible for the development of our modern four-layer ocean current and heat distribution system.

To come to her conclusions, Katz looked at the uptake of different elemental isotopes in the skeletons of small organisms found in ocean sediments. The organisms, known as benthic foraminifera, are found in extremely long cores of sediments drilled from the bottom of the ocean floor.

During their lifetime, foraminifera incorporate certain elements and elemental isotopes depending on environmental conditions. By analyzing the ratios of different isotopes and elements, the researchers are able to reconstruct the past environmental conditions that surrounded the foraminifera during their life. Specifically, they looked at isotopes of oxygen and carbon, along with ratios of magnesium versus calcium. More detailed information on Katz's isotopic analysis methods can be found at http://green.rpi.edu/archives/fossils/index.html.

Analysis of these isotopes from sediment cores extracted directly off the North American Atlantic coast showed the earliest evidence for the Antarctic Intermediate Waters, which circulates strictly as a direct consequence of the ACC. This finding is the first evidence of the effects of shallow ACC formation. The findings place development of the ACC's global impact much closer to the time that Antarctica separated from South America. It had previously been thought that the currents moving through this new continental gateway could not be strong enough at such shallow depths to affect global ocean circulation.

Katz points out that the larger cooling trend addressed in the paper has been punctuated by many short, but often significant, episodes of global warming. Such ancient episodes of warming are another significant aspect of her research program, and play an important role in understanding the modern warming of the climate occurring on the planet.

"By reconstructing the climates of the past, we can provide a science-based means to explore or predict possible system responses to the current climate change," Katz said.

Katz is joined in the research by Benjamin Cramer of Theiss Research; J.R. Toggweiler of Geophysical Fluid Dynamics Lab/NOAA; Chengjie Liu of ExxonMobil Exploration Co.; Bridget Wade of University of Leeds; and Gar Esmay, Kenneth Miller, Yair Rosenthal, and James Wright of Rutgers University

Scientists Argue Against Conclusion That Bacteria Consumed Deepwater Horizon Methane

Fire boat response crews battle the blazing remnants of the off shore oil rig Deepwater Horizon April 21, 2010. (Credit: U.S. Coast Guard photo)

ScienceDaily (May 29, 2011) — A technical comment published in the May 27 edition of the journal Science casts doubt on a widely publicized study that concluded that a bacterial bloom in the Gulf of Mexico consumed the methane discharged from the Deepwater Horizon well.

The debate has implications for the Gulf of Mexico ecosystem as well as for predictions of the effect of global warming, said marine scientist and lead author Samantha Joye, University of Georgia Athletic Association Professor in Arts and Sciences.

Based on methane and oxygen distributions measured at 207 stations in the Gulf of Mexico, a study published in the January 21, 2011 edition of Science concluded that "nearly all" of the methane released from the well was consumed in the water column within approximately 120 days of the release. In the current paper inScience, Joye and co-authors from 12 other institutions make the case that uncertainties in the hydrocarbon discharge from the blowout, oxygen depletion fueled by processes other than methane consumption, a problematic interpretation of genetic data and shortcomings of the model used by the authors of the January study challenge the attribution of low oxygen zones to the oxidation of methane gas.

"Our goal is to understand what happened to the methane released from the Macondo discharge and in the larger framework, to better understand the factors that regulate microbial methane consumption following large-scale gas releases," said Joye, a professor in the UGA Franklin College of Arts and Sciences. "I believe there is still a lot to learn about the environmental factors that regulate methane consumption in the Gulf's waters and elsewhere."

Joye and her co-authors note that low levels of oxygen are known to occur in the Gulf of Mexico because of bacterial consumption of carbon inputs from the Mississippi River as well as the bacterial consumption of hydrocarbons that naturally seep from the seafloor. The researchers point out that given the uncertainty in oxygen and methane budgets, strong supporting evidence is required to attribute oxygen depletion to methane removal; however, a study published in the October 8, 2010 edition of Science showed low measured rates of methane consumption by bacteria. Joye and her co-authors note that samples from the control stations and the low-oxygen stations that were analyzed for unique genetic markers in the January 2011 study showed no significant difference in the abundance of methane consuming bacteria. Joye and her colleagues also argue that the model the study used neglected important factors that affect the transport and biodegradation of methane, and that it only provided a tentative match of the observational data.

Methane is a potent greenhouse gas, and understanding the fate of the methane released from the Deepwater Horizon well has implications for the entire planet, since global warming is likely to accelerate the release of methane that is currently trapped in hydrates on the seafloor. Based on the conclusion that bacteria had rapidly consumed the methane released from the Deepwater Horizon well, the January 2011 Science paper suggested that methane released from the oceans may not be likely to amplify an already warming climate.

Joye and her colleagues note that several other studies have found that considerable amounts of methane released from natural deep-sea vents are not consumed by microbes. The most vulnerable store of methane hydrates is not in the Gulf of Mexico, they also point out, but in the deposits that underlie the shallow waters of the Arctic.

"A range of data exists that shows a significant release of methane seeping out at the seafloor to the atmosphere, indicating that the microbial biofilter is not as effective," Joye said. "Importantly for the future of the planet, there is even less evidence for a strong biofilter of methane hydrate destabilized in the shallow Arctic settings."

Joye's co-authors include Ira Leifer, University of California, Santa Barbara; Ian MacDonald, Jeffery Chanton and Joel Kostka, Florida State University; Christof Meile, University of Georgia; Andreas Teske, University of North Carolina, Chapel Hill; Ludmila Chistoserdova and Evan Solomon, University of Washington, Seattle; Richard Coffin, U.S. Naval Research Laboratory; David Hollander, University of South Florida; Miriam Kastner, Scripps Institution of Oceanography, University of California, San Diego; Joseph Montoya, Georgia Institute of Technology; Gregor Rehder, Leibniz Institute for Baltic Sea Research; Tina Treude, Leibniz Institute of Marine Sciences and; Tracy Villareal, University of Texas at Austin.

Teasing Apart Galaxy Collisions: Spitzer Photo Atlas of Galactic 'Train Wrecks'

This montage shows three examples of colliding galaxies from a new photo atlas of galactic "train wrecks." The new images combine observations from NASA's Spitzer Space Telescope, which observes infrared light, and NASA's Galaxy Evolution Explorer (GALEX) spacecraft, which observes ultraviolet light. By analyzing information from different parts of the light spectrum, scientists can learn much more than from a single wavelength alone, because different components of a galaxy are highlighted. The panel at far left shows NGC 470 (top) and NGC 474 (bottom); at top right are NGC 3448 and UGC 6016; at bottom right are NGC 935 and IC 1801. In this representative-color image, far-ultraviolet light from GALEX is blue, 3.6-micron light from Spitzer is cyan, 4.5-micron light from Spitzer is green, and red shows light at 5.8 and 8 microns from Spitzer. (Credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA)

ScienceDaily — Five billion years from now, our Milky Way galaxy will collide with the Andromeda galaxy. This will mark a moment of both destruction and creation. The galaxies will lose their separate identities as they merge into one. At the same time, cosmic clouds of gas and dust will smash together, triggering the birth of new stars.

To understand our past and imagine our future, we must understand what happens when galaxies collide. But since galaxy collisions take place over millions to billions of years, we can't watch a single collision from start to finish. Instead, we must study a variety of colliding galaxies at different stages. By combining recent data from two space telescopes, astronomers are gaining fresh insights into the collision process.

"We've assembled an atlas of galactic 'train wrecks' from start to finish. This atlas is the first step in reading the story of how galaxies form, grow, and evolve," said lead author Lauranne Lanz of the Harvard-Smithsonian Center for Astrophysics (CfA).

Lanz presented her findings May 25 at the 218th meeting of the American Astronomical Society.

The new images combine observations from NASA's Spitzer Space Telescope, which observes infrared light, and NASA's Galaxy Evolution Explorer (GALEX) spacecraft, which observes ultraviolet light. By analyzing information from different parts of the light spectrum, scientists can learn much more than from a single wavelength alone, because different components of a galaxy are highlighted.

GALEX's ultraviolet data captures the emission from hot young stars. Spitzer sees the infrared emission from warm dust heated by those stars, as well as from stellar surfaces. Therefore, GALEX's ultraviolet data and Spitzer's infrared data highlight areas where stars are forming most rapidly, and together permit a more complete census of the new stars.

In general, galaxy collisions spark star formation. However, some interacting galaxies produce fewer new stars than others. Lanz and her colleagues want to figure out what differences in physical processes cause these varying outcomes. Their findings will also help guide computer simulations of galaxy collisions.

"We're working with the theorists to give our understanding a reality check," said Lanz. "Our understanding will really be tested in five billion years, when the Milky Way experiences its own collision."

Lanz's co-authors are Nicola Brassington (Univ. of Hertfordshire, UK); Andreas Zezas (Univ. of Crete, Greece, and CfA); Howard Smith and Matt Ashby (CfA); Christopher Klein (UC Berkeley); and Patrik Jonsson, Lars Hernquist, and

Biological Computers: Genetically Modified Cells Communicate Like Electronic Circuits

Genetically modified cells can be made to communicate with each other as if they were electronic circuits. (Credit: University of Gothenburg

ScienceDaily — Genetically modified cells can be made to communicate with each other as if they were electronic circuits. Using yeast cells, a group of researchers at the University of Gothenburg, Sweden, has taken a groundbreaking step towards being able to build complex systems in the future where the body's own cells help to keep us healthy. The study was presented recently in an article in the scientific journal Nature.

"Even though engineered cells can't do the same job as a real computer, our study paves the way for building complex constructions from these cells," says Kentaro Furukawa at the University of Gothenburg's Department of Cell- and Molecular Biology, one of the researchers behind the study. "In the future we expect that it will be possible to use similar cell-to-cell communication systems in the human body to detect changes in the state of health, to help fight illness at an early stage, or to act as biosensors to detect pollutants in connection with our ability to break down toxic substances in the environment."

Combining biology and technology

Synthetic biology is a relatively new area of research. One application is the design of biological systems that are not found in nature. For example, researchers have successfully constructed a number of different artificial connections within genetically modified cells, such as circuit breakers, oscillators and sensors.

Some of these artificial networks could be used for industrial or medical applications. Despite the huge potential for these artificial connections, there have been many technical limitations to date, mainly because the artificial systems in individual cells rarely work as expected, which has a major impact on the results.

Biotechnology challenges the world of computers

Using yeast cells, the research team at the University of Gothenburg has now produced synthetic circuits based on gene-regulated communication between cells. The yeast cells have been modified genetically so that they sense their surroundings on the basis of set criteria and then send signals to other yeast cells by secreting molecules. The various cells can thus be combined like bricks of Lego to produce more complicated circuits. Using a construction of yeast cells with different genetic modifications, it is possible to carry out more complicated "electronic" functions than would be the case with just one type of cells.

The University of Gothenburg research team is headed by professor Stefan Hohmann, and also comprises Kentaro Furukawa and Jimmy Kjellén.

The article Distributed biological computation with multicellular engineered networks, published in the scientific journal Natureon 8 December, was the result of a partnership with two Spanish research teams at Universitat Pompeu Fabra in Barcelona. The work forms part of the EU CELLCOMPUT